David, you _____play with the valuable bottle; you_______ break it.

  —The winner is a tall and thin boy with glasses!—Well，it________ be Mike.  He doesn’t wear any glasses.

--Listen! Tom is singing in the next room.--It _______ be Tom. He has gone to Shanghai. 

—May I smoke here?    —If you _____, choose a seat in the smoking section.

The soccer team has been doing well this season，so they       win the championship．